Composite material including rigid foam with inorganic fillers

ABSTRACT

A composite material includes, in an exemplary embodiment a polyurethane foam and a plurality of inorganic particles dispersed therein. The polyurethane foam is formed from a reaction mixture that includes a first polyether polyol having a first molecular weight and a functionality of about 3 or less, a second polyether polyol having a second molecular weight less than the first molecular weight and a functionality of greater than about 3, and at least one isocyanate. The ratio of an amount of the first polyol in the reaction mixture to an amount of the second polyol in the reaction mixture is between about 1:1 to about 5:1.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation and claims priority to U.S. patentapplication Ser. No. 11/190,760 entitled “Composite Material IncludingRigid Foam With Inorganic Fillers,” by Fyodor A. Shutov, filed Jul. 27,2005, which is assigned to the current assignee hereof and incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

This invention relates generally to composite materials, and moreparticularly, to composite materials based on rigid polyurethane foamsand reinforcing mineral fillers.

Polyurethane foams are commonly prepared by reacting isocyanate withhydrogen-containing compounds having reactive hydroxyl groups, forexample, polyester or polyether polyols. The reaction occurs in thepresence of a catalyst, and a blowing agent is provided in order toproduce an expanded, cellular product. The blowing agent can be producedchemically by the interaction of the isocyanate with water to generateCO₂ gas. In low density, high expanding systems, a blowing agent such astrichlorofluoromethane is added which vaporizes at the outset of thereaction. Polyurethane foam systems are commonly prepared as twocomponents, the isocyanate component being maintained separate from thepolyol-catalyst-blowing agent component until the time of use.

Structural articles formed from polyurethane foams usually includefillers to increase the strength of the polyurethane foam. U.S. Pat. No.4,661,533 to Stobby describes a rigid polyurethane modifiedpolyisocyanurate foam containing fly ash as a filler that is used forbuilding insulation. However, structural building products, for examplesynthetic lumber, require higher density foams than those taught byStobby.

BRIEF DESCRIPTION OF THE INVENTION

In one aspect, a composite material is provided that includes apolyurethane foam and a plurality of inorganic particles dispersedtherein. The polyurethane foam is formed from a reaction mixture thatincludes a first polyether polyol having a first molecular weight and afunctionality of about 3 or less, a second polyether polyol having asecond molecular weight less than the first molecular weight and afunctionality of about 3 or greater, and at least one isocyanate. Theratio of an amount of the first polyol in the reaction mixture to anamount of the second polyol in the reaction mixture is between about 1:1to about 5:1.

In another aspect, a synthetic lumber article is provided that includesa composite material. The composite material includes a polyurethanefoam and a plurality of inorganic particles dispersed therein. Thepolyurethane foam is formed from a reaction mixture that includes afirst polyether polyol having a first molecular weight and afunctionality of about 3 or less, a second polyether polyol having asecond molecular weight that is less than the first molecular weight anda functionality of about 3 or greater, and at least one isocyanate. Theratio of an amount of the first polyol in the reaction mixture to anamount of the second polyol in the reaction mixture is between about 1:1to about 5:1.

In another aspect, a method of producing a composite material includinga polyurethane foam and a plurality of inorganic particles dispersedtherein is provided. The method includes mixing a first polyether polyolhaving a first molecular weight and a functionality of about 3 or lesswith a second polyether polyol having a second molecular weight which isless than the first molecular weight and a functionality of about 3 orgreater to form a polyol mixture wherein a ratio of an amount of thefirst polyol in the mixture to an amount of the second polyol in themixture is between about 1:1 to about 5:1. The method also includesadding a plurality of inorganic particles to the mixture where theplurality of inorganic particles are present in amount of about 30weight percent to about 85 weight percent, the weight percent based onthe total weight of the mixture, and adding at least one isocyanate tothe polyol mixture.

DETAILED DESCRIPTION OF THE INVENTION

A composite material that is formed from a thermosetting polyurethanebinder and a plurality of inorganic fillers dispersed therein isdescribed in detail below. The polyurethane foam binder is formed fromthe reaction of two or more polyether polyols with aromatic isocyanates.The mineral fillers can be particulate materials, for example, fly ash,bottom ash, fine sand, ceramic particles, and glass particles, and/ormineral fibers, for example, glass fibers, graphite fibers, carbonfibers, ceramic fibers, vermiculite fibers, basalt fibers, andvallostonite fibers, as well as inorganic fibers. The composite materialcan be formed into any shape and be used for a replacement of naturalwood as an artificial or synthetic lumber. For example, the compositematerial is suitable for use as railroad ties, roof shingles, siding forhomes, fence posts, window and door frames, and also a replacement forsome ceramic and concrete building materials. The composite materialexhibits high flexural strength and impact resistance along with lowthermal expansion and contraction compared to natural and knownsynthetic wood. The composite material also exhibits higher fireresistance and lower water absorption compared to natural and knownsynthetic wood.

The composite material, in an exemplary embodiment, is formed from areaction mixture containing liquid and solid components. The liquidcomponents include two or more polymeric and/or oligomeric polyetherpolyols, polymeric, oligomeric, or monomeric polyisocyanates, aminecatalysts, organometallic catalysts, and a blowing agent. The liquidcomponents can also include surfactants, wetting agents, plasticizers,light and heat stabilizers and antioxidants, flame retardants, moldrelease agents, and antistatic agents. Solid components of the reactionmixture include particulate and/or filament mineral and/or organicfillers, chopped and/or milled reinforcing fibers, and pigments. Thesolid components can also include light and heat stabilizers andantioxidants, antistatic agents, mold release agents, and flameretardants.

Polyether polyols used to form the composite material includelow-viscosity polyether polyols having a first molecular weight and afunctionality of about 3 or less, and in one embodiment, a functionalityfrom about 2 to about 3. Also, polyether polyols having a secondmolecular weight lower than the first molecular weight and afunctionality of about 3 or greater are used in the reaction mixturewhere greater than 50 weight percent of the polyols in the mixture has afunctionality of 3 or less. Particularly, in one embodiment, the ratioof the weight of polyether polyols having a functionality of about 3 orless to the weight of polyether polyols having a functionality of about3 or greater is about 1:1 to about 5:1, and in another embodiment fromabout 1.5:1 to about 3.0:1. Polyether polyols with a functionality ofabout 3 or less provide flexibility to the composite material whilepolyether polyols with a functionality of greater than about 3 providerigidity to the composite material.

Suitable polyether polyols include, but are not limited to,polypropylene glycol, polyethylene glycol, polytetramethylene etherglycol, glycerol, neopentyl glycol, 1,2-pentane diol, pentaerythritoladducts, 1,6-hexane diol, 1,3-butylene glycol, trimethylolpropaneadducts, trimethylolethane adducts, ethylendiamine adducts, anddiethylenetriamine adducts. Polyether polyols are commercially availablefrom, for example, Bayer Corporation under the trademark MULTRANOL.

Useful polyisocyanates include aromatic polyisocyanates. Suitableexamples of aromatic polyisocyanates include 4,4-diphenylmethanediisocyanate (methylene diphenyl diisocyanate), 2,4- or 2,6-toluenediisocyanate, including mixtures thereof, p-phenylene diisocyanate,tetramethylene and hexamethylene diisocyanates, 4,4-dicyclohexylmethanediisocyanate, isophorone diisocyanate, mixtures of 4,4-phenylmethanediisocyanate and polymethylene polyphenylisocyanate. Higherpolyisocyanates such as triisocyanates can be used, for example,4,4,4-triphenylmethane triisocyanate 1,2,4-benzene triisocyanate;polymethylene polyphenyl polyisocyanate; and methylene polyphenylpolyisocyanate. Isocyanates are commercially available from Bayer USA,Inc. under the trademarks MONDUR and DESMODUR. The ratio of isocyanateto polyol (isocyanate index), based on equivalent weights of OH groups(hydroxyl index) and NCO groups, in one embodiment, range from about0.5:1 to about 1.5:1, and in another embodiment, from about 0.8:1 toabout 1.2:1.

In the exemplary embodiment, two different catalysts are used. A firstcatalyst (gel catalyst) is selected to promote the gelling ractionbetween hydroxyl and isocyanate groups and accelerate curing of thesystem, for example, amine catalysts. Suitable amines can includeprimary, secondary, and tertiary amines. Some examples of aminesinclude, but are not limited to, diisopropanolamine, triethanolamine,triethylamine, monoethanolamine, dimethylethylamine,dimethylethanolamine, and 2-amino-2-methylpropanol triethylene diamine.The amount of amine catalyst ranges from about 0.01 weight percent toabout 0.1 weight percent A second catalyst (foaming catalyst) isselected to promote the reaction between water and isocyanate groups andaccelerate generation of CO₂ used as a blowing agent to foam the system,for example, organometallic catalysts, including carboxylates andmercatides. Some non-limiting examples of organometallic catalystsinclude organotin compounds, including dibutyltin dilaurate anddibutyltin oxide. The amount of organometallic catalyst ranges fromabout 0.001 weight percent to about 0.01 weight percent. In otherembodiments, more than two catalysts can be used. Further, both the geland foaming catalysts can be delayed action catalysts to extend curingand/or foaming time, for example, UL-29 and A-530 catalysts,commercially available from General Electric Company.

Surfactants and wetting agents can be added to the reaction mixture tofacilitate the mixing of the solid components into the liquid componentsof the reaction mixture. Anionic and cationic surfactants can be used,for example, silicone surfactants, such as DC-197 or DC-193 commerciallyavailable from Air Products, Inc, or Niax Silicone L-1602 commerciallyavailable from General Electric Company. The amount of surfactant usedis about 0.5 weight percent or less.

A blowing agent is used to facilitate the foaming of the polyurethanebinder and to control the density of the composite material. Organicblowing agents, for example, halogenated hydrocarbons, hexanes, andfluorocarbons can be used. Also, water can be used as a blowing agentbecause of the formation of carbon dioxide from the reaction of waterand isocyanate. When water is used as the blowing agent, from about 0.1weight percent to about 3.0 weight percent of water is added to thereaction mixture. Varying the amount of blowing agent used facilitatescontrolling the density of the composite material. In one embodiment,the density of the composite material is about 20 pounds per cubic foot(lbs/ft³) to about 90 lbs/ft³, and in another embodiment from about 30lbs/ft³ to about 75 lbs/ft³.

As explained above, the solid components of the reaction mixture includeparticulate mineral fillers, chopped and/or milled reinforcing fibers,and pigments. The particulate mineral fillers add strength to thecomposite material and, in one embodiment, are present in the reactionmixture from about 30 weight percent to about 85 weight percent, and inanother embodiment, from about 50 weight percent to about 85 weightpercent. Suitable particulate mineral fillers include, for example, flyash, bottom ash, fine sand, ceramic particle, glass particles, andmixtures thereof. A broad particle size distribution of particulatemineral fillers can provide for particulate packing which facilitatesincorporating high levels of particles in the reaction mixture and thecomposite material. Particle size distributions of the particulatemineral fillers, in one embodiment, range from about 5 μm to about 200μm, and in another embodiment, from about 20 μm to about 50 μm.

Suitable reinforcing fibers for use in forming the composite materialinclude, but are not limited to, inorganic fibers, glass fibers,graphite fibers, carbon fibers, ceramic fibers, vermiculite fibers,basalt fibers, vallostonite fibers, and mixtures thereof. Whenreinforcing fibers are present in the composite material, they arepresent in amount ranging between about 1.0 weight percent to about 15weight percent.

To provide a uniform color to the composite material, pigments can beadded to the reaction mixture in amounts ranging from about 1.0 weightpercent to about 15 weight percent. Any suitable mineral or organicpigment or mixtures of pigments can be incorporated into the compositematerial, for example, iron oxide, titanium dioxide, and carbon black.Other additives can be added to the reaction mixture to provide desiredproperties to the composite materials, for example, heat stabilizers,light stabilizers, and antioxidants.

To provide for uniform mixing of the solid components with minorquantities of liquid components, and thereby control mechanicalproperties and density, plastisizers/lubricants can be added up to about5 weight percent. Suitable plastisizers include viscose natural orsynthetic aromatic hydrocarbons, or mixtures of aromatic andnon-aromatic hydrocarbons, for example, VYCEL, commercially availablefrom Crowley Chemical Co.

As explained above, the composite material is formed from a reactionmixture containing liquid and solid components. The solid components arepre-blended with the liquid components, minus the isocyantes, in anysuitable mixing equipment, for example, mixing tanks and extruders. Itis important that the solid components, such as the mineral fillerparticles, the pigments, and the reinforcing fibers, are uniformlydispersed in the liquid components, such as the polyether polyols. Afterthese liquid and solid components are thoroughly mixed, the isocyanateis added to start the foaming and curing reactions. The mixture is thenpoured into a mold or onto a conveyorized continuous mold for finalfoaming, curing, solidification, texturing of the surface of thecomposite material, and cutting to length.

The above described composite material can be molded into any shapecontaining any desired surface texture and be used for a replacement ofnatural wood as an artificial or synthetic lumber. For example, thecomposite material is suitable for use as railroad ties, roof shingles,siding for homes, fence posts, window and door frames, and also areplacement for some ceramic and concrete building materials. Thecomposite material exhibits high flexural strength and impact resistancealong with low thermal expansion and contraction compared to wood. Thecomposite material also exhibits high fire resistance and low waterabsorption compared to wood. Also, the rigidity of composite materialcan be varied by varying the ratio of the rigid and flexible polyetherpolyols. The strength and impact resistance can also be varied byadjusting the relative amounts of particulate fillers and reinforcingfibers.

The invention will be further described by reference to the followingexamples which are presented for the purpose of illustration only andare not intended to limit the scope of the invention. Unless otherwiseindicated, all amounts are listed as parts by weight.

EXAMPLES 1-4

Examples 1 through 4 compare varying the first polyol to the secondpolyol ratios of 1.4:1, 1.3:1, 1.2:1, and 1.1:1 respectively. Thecomposite materials of Examples 1-4 listed below in Table 1 wereprepared by mixing the following materials in an extruder at roomtemperature. Each resulting composite material was extruded through anextruder head into a mold under pressure. The composite material wascooled and removed from the mold.

TABLE 1 Component Example 1 Example 2 Example 3 Example 4 Product FirstPolyol 225.0 225.0 225.0 225.0 Acclain 703¹ Second Polyol 160.4 173.1187.5 204.5 Multranol 4035¹ Polyol Ratio: 1.40 1.30 1.20 1.10 PolymericMDI 332.6 345.6 363.5 381.2 Mondur MR (Light)¹ Isocyanate Index 1.1201.120 1.110 1.133 Surfactant 3.85 3.85 3.85 3.85 Niax Silicone L-1602²Water 2.00 2.00 2.42 2.00 Plasticizer 18.24 18.24 23.16 18.24 Vycel-U³Catalyst 1 0.56 0.79 0.59 0.79 UL-29² Catalyst 2 1.45 1.20 1.73 1.20A-530² Pigment 148 148 148 148 BN-2530⁴ Fiberglass 278 278 278 278366-113 OCF⁵ Fly Ash 1911 2110 2160 2060 Navajo Fly Ash⁶ Total Weight3081.10 3305.78 3393.75 3322.78 General Properties Example 1 Example 2Example 3 Example 4 Density (lb/ft³) 47.9 52.1 45.9 43.6 Avg. FlexStress (psi) 2330 3223 2948 3048 Flex/Density Ratio 49 62 64 70 FlexModulus (Kpsi) 543 674 656 805 Impact Avg. (ft/lbs.) 116 145 132 129¹Commercially available from Bayer Corporation. ²Commercially availablefrom General Electric Company. ³Commercially available from CrowleyChemical Corporation. ⁴Commercially available from InterstarCorporation. ⁵Commercially available from Ashland Chemical Company.⁶Commercially available from Headwater Resources Company.

EXAMPLES 5-6

Examples 5 and 6 compare varying a isocyanate index of 1.051 and 1.180at a constant ratio of 1.2 of the first polyol to the second polyol. Thecomposite materials of Examples 5 and 6 listed below in Table 2 wereprepared by mixing the following materials in an extruder at roomtemperature. Each resulting composite material was extruded through anextruder head into a mold under pressure. The composite material wascooled and removed from the mold.

TABLE 2 Component Example 5 Example 6 Product First Polyol 225.0 225.0Acclaim 703 Second Polyol 187.5 187.5 Multranol 4035 Polyol Ratio: 1.201.20 Polymeric MDI 326.1 366.1 Mondur MR (Light) Isocyanate Index 1.0511.180 Surfactant 3.85 3.85 Niax Silicone L-1602 Water 2.00 2.00Plasticizer 23.12 18.24 Vycel-U Catalyst 1 0.50 0.49 UL-29 Catalyst 21.20 1.20 A-530 Pigment 148 148 BN-2530 Fiberglass 348 278 366-113 OCFFly Ash 2160 2160 Navajo Fly Ash Total Weight 3425.27 3390.38 GeneralProperties Example 5 Example 6 Density (lb/ft³) 45.6 52.9 Avg. FlexStress (psi) 1918 3629 Flex/Density Ratio 42 69 Flex Modulus (Kpsi) 322667 Impact Avg. (ft/lbs.) 48 129

EXAMPLES 7-8

Examples 7 and 8 compares the effect of a plasticizer at a constantisocyanate index of 1.028 and at a constant ratio of 1.8 of the firstpolyol to the second polyol. The composite materials of Examples 7 and 8listed below in Table 3 were prepared by mixing the following materialsin an extruder at room temperature. Each resulting composite materialwas extruded through an extruder head into a mold under pressure. Thecomposite material was cooled and removed from the mold.

TABLE 3 Component Example 7 Example 8 Product First Polyol 225.0 225.0Acclaim 703 Second Polyol 125.0 125.0 Multranol 4035 Polyol Ratio: 1.801.80 Polymeric MDI 302.0 306.7 Mondur MR (Light) Isocyanate Index 1.0281.028 Surfactant 3.00 3.00 Niax Silicone L-1602 Water 2.58 2.40Plasticizer 0.00 33.00 V895BL Catalyst 1 0.49 0.80 UL-29 Catalyst 2 0.880.69 A-530 Pigment 125 125 BN-2530 Fiberglass 278 348 366-113 OCF FlyAsh 1910 1910 Navajo Fly Ash Total Weight 2971.95 3079.59 GeneralProperties Example 7 Example 8 Density (lb/ft³) 43.6 44.4 Avg. FlexStress (psi) 1528 2201 Flex/Density Ratio 35 50 Flex Modulus (Kpsi) 435400 Impact Avg. (ft/lbs.) 76 130

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

What is claimed is:
 1. A composite material usable as synthetic lumber,comprising a polyurethane foam and a plurality of inorganic particlesdispersed therein, wherein: the polyurethane foam is formed from areaction mixture comprising at least one polyisocyanate, a firstflexible polyether polyol having a first molecular weight and afunctionality of about 3 or less, and a second rigid polyether polyolhaving a second molecular weight and a functionality of about 3 orgreater, wherein the second molecular weight is less than the firstmolecular weight, and a wt % ratio of the first flexible polyol to thesecond rigid polyol ranges from about 1:1 to about 5:1; the plurality ofinorganic particles is present in an amount of about 50 wt % to about 85wt % based on the total weight of the composite material, the inorganicfiller particles including fly ash and glass fibers; the compositematerial has a density in a range from about 30 lbs/ft³ to about 52.1lbs/ft³; and the composite material has an average flexural stress of atleast 2330 psi.
 2. The composite material of claim 1, wherein the glassfibers are present in an amount of 1 wt % to about 15 wt % based on thetotal weight of the composite material.
 3. The composite material ofclaim 1, wherein the reaction mixture further comprises a first catalystcomprising an amine compound, and a second catalyst comprising anorganometallic compound.
 4. The composite material of claim 3, whereinthe first catalyst comprises a tertiary amine, and the second catalystcomprises an organotin compound.
 5. The composite material of claim 1,wherein the reaction mixture further comprises an aromatic hydrocarbonin an amount of up to 5 wt % based on the total weight of the compositematerial.
 6. The composite material of claim 1, wherein the inorganicparticles further comprise at least one of a bottom ash, fine sand,ceramic particles, glass particles, graphite fibers, carbon fibers,ceramic fibers, vermiculite fibers, basalt fibers, vallostonite fibers,or any combination thereof.
 7. A method of producing a compositematerial usable as synthetic lumber, comprising a polyurethane foam anda plurality of inorganic particles dispersed therein, the methodcomprising: mixing a first flexible polyether polyol having a firstmolecular weight and a functionality of about 3 or less with a secondrigid polyether polyol having a second molecular weight and afunctionality of about 3 or greater to form a polyol mixture, wherein aratio of an amount of the first polyol in the mixture to an amount ofthe second polyol in the mixture is between about 1:1 to about 5:1, thesecond molecular weight less than the first molecular weight; adding upto about 5 weight percent based on the total weight of the compositematerial of an aromatic hydrocarbon; adding an amount of about 50 wt %to about 85 wt % of the plurality of inorganic particles to the mixture,the plurality of inorganic particles include fly ash and glass fibers,adding at least one polyisocyanate to the polyol mixture; and extrudingthe mixture into a mold to form a composite material having a densityfrom about 30 lbs/ft³ to about 52.1 lbs/ft³ and an average flexuralstress of at least 2330 psi.
 8. The method of claim 7, wherein the glassfibers are present in an amount of 1 wt % to about 15 wt % based on thetotal weight of the composite material.
 9. The method of claim 7,wherein the reaction mixture further comprises a blowing agent.
 10. Themethod of claim 9, wherein the blowing agent comprises water.
 11. Themethod of claim 7, wherein the reaction mixture further comprises afirst catalyst comprising an amine compound, and a second catalystcomprising an organometallic compound.
 12. The method of claim 11,wherein the first catalyst comprises a tertiary amine, and the secondcatalyst comprises an organotin compound.
 13. The method of claim 7,wherein the inorganic particles further comprise at least one of abottom ash, fine sand, ceramic particles, glass particles, graphitefibers, carbon fibers, ceramic fibers, vermiculite fibers, basaltfibers, vallostonite fibers, or any combination thereof.
 14. A syntheticlumber article comprising a composite material, the composite materialcomprising a polyurethane foam and a plurality of inorganic fillerparticles, wherein: the polyurethane foam is formed from at least onepolyisocyanate, a first flexible polyether polyol having a firstmolecular weight and a functionality of about 3 or less, and a secondrigid polyether polyol having a second molecular weight and afunctionality of about 3 or greater, wherein the second molecular weightbeing less than the first molecular weight, and a wt % ratio of thefirst flexible polyol to the second rigid polyol ranges from about 1:1to about 5:1; the plurality of inorganic filler particles is present inan amount of about 50 wt % to about 85 wt % based on the total weight ofthe composite material, the inorganic filler particles including fly ashand glass fibers; the composite material has a density in a range fromabout 30 lbs/ft³ to about 52.1 lbs/ft³; and the composite material hasan average flexural stress of at least 2330 psi.
 15. The syntheticlumber article of claim 14, adapted for use as a railroad tie, a roofshingle, a siding for homes, a fence post, a window frame, a door frame,or a replacement for ceramic and concrete building materials.
 16. Thesynthetic lumber article of claim 14, wherein the composite materialcomprises a textured surface.